textproduct: Quad Cities

KEY MESSAGES

- Hot and humid conditions are forecast to continue through Saturday, with peak afternoon heat indices of 95 to 100. Heat indices over 100 are possible Saturday afternoon south of Interstate 80.

- Scattered afternoon/evening showers and storms (30 to 50%) are possible today. Severe thunderstorms are not expected.

- On Saturday, isolated to scattered showers and storms (20 to 40%) are possible Saturday afternoon and evening along and south of Interstate 80. Isolated severe storms are possible, mainly in northwest Illinois. - There will be Canadian wildfire smoke at times into this weekend with mainly hazy skies. However thicker concentrations near surface and unhealthy air quality is possible across parts of northwest Illinois through tonight.

- Next week a pattern change wiil bring periodic storm chances as well as cooler temperatures after Tuesday.

SHORT TERM /THROUGH TONIGHT/

Issued at 114 AM CDT Fri Jul 17 2026

Temperatures today will once again be in the lower 90s with dew points in the lower to mid 70s. This will result in heat indices of 95 to 100 during the afternoon. A shortwave lifting northeastward across the area during the day will bring a 30 to 50% chance of showers and storms to the area through Friday evening. We are expecting more coverage than yesterday with a stronger shortwave moving across the area. The potential cloud cover and precipitation may inhibit temperatures today and keep heat indices lower but may cause increases in humidity with shortlived showers. Rainfall amounts of 0.25 to 0.50 inches are possible with isolated amounts up to 1 inch in the strongest showers and storms. Severe thunderstorms are not expected. Low temperatures Friday night will be warm with lows continuing to be in the mid to upper 70s.

An Air Quality Alert remains in effect until midnight tonight for Jo Daviess and Stephenson Counties. A frontal boundary draped across these counties may allow Canadian wildfire smoke to make it to the surface. Both the RAP13 and HRRR show smoke improving as this front shifts to the east Friday evening.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 114 AM CDT Fri Jul 17 2026

On Saturday, another shortwave trough is forecast to pass to our north and east through Saturday night. This will push a cool front southward across the area Saturday into Saturday evening. Models have this boundary near the area to start the period. The frontal timing will impact temperatures and dewpoints across the area with timing of front south of the Highway 30 corridor during the afternoon and evening hours. This frontal timing will allow temperatures to push into the lower to mid 90s across the area with continued dewpoints in the lower to mid 70s ahead of the front. This may lead to heat indices during the afternoon and evening in excess of 100 degrees especially south of Interstate 80 where a heat advisory may be needed with more widespread heat indices over 100. LREF probabilities of heat indices over 100 on Saturday head of the front are 40 to 60 percent with 70 percent south of a Fairfield to Burlington to Monmouth line.

There is a 20 to 40 % chance of showers and storms ahead of this front but the better forcing remains to our north and east. Models are showing 0 to 6 km shear of 20 to 30 knots with up to 2000 J/KG mainly along and south of Interstate 80 on Saturday. For this reason, the Storm Prediction Center has the area along and east of a line from Burlington Iowa to Sterling Rock Falls Illinois in a Marginal (level 1 out of 5) Risk of severe storms. Damaging winds gusts will be the main threat.

In the wake of Saturdays storm system, northwesterly flow aloft is forecast to develop and continue through the remainder of the week. After a brief reprieve from warmer temperatures on Sunday, heat and humidity is forecast to build into the area on Monday ahead of another shortwave and stronger cold front that moves across the area on Tuesday with another round of showers and storms. Cooler temperatures build into the area Wednesday onward with high temperatures closer to normal for late July but temperatures may be cooler with a model spread of about 10 degrees Wednesday onward. This northwest flow will also allow several shortwaves moving through the flow and produce periodic chances of showers and storms.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1231 AM CDT Fri Jul 17 2026

VFR conditions are forecast through 18 UTC Friday. A disturbance lifting across the area on Friday will bring the risk of showers and storms to eastern Iowa TAF sites after 18 UTC on Friday with periods of MVFR ceilings and visibilities. Showers and storms will come to an end after 00 UTC and may linger through 03 UTC but confidence is low on the exact timing of showers and storms. Showers and storms may hold off at KCID and KDBQ until after 21 UTC. Winds are southwesterly through the period with speeds of 5 to 10 knots between 15 and 00 UTC.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...Air Quality Alert until midnight CDT tonight for ILZ001-002. MO...None.